Adjustable impeller



Dec. 27, 1966 'c. H. BODNER 3,294,175

ADJUSTABLE IMPELLER Filed Oct. 11. 1965 IMAM/roe. C/MEL ES hf 6004/52United States Patent 3,294,175 ADJUSTABLE IMPELLER Charles H. Bodner,2413 127th Ave. NE., Bellevue, Wash. 98004 Filed Oct. 11, 1965, Ser. No.494,426 2 Claims. (Cl. 170160.61)

The present invention relates to impellers or fan devices; moreparticularly, the invention relates to impellers or fans which directimpelled fluid in a converging beam for spot blowing.

In conventional impellers or fans, a centrifugal as well as forwardmotion is given to the fluid by rotation of the blades. Substantialamounts of air are therefore lost at the blade tips and the pattern ofair flow is a diverging or spreading one, wherein the concentration ofair flow diminishes as the area of the stream increases. Tip lossesrepresent losses in efiiciency and of power. Moreover, noises areproduced by the blade tips.

The present invention provides a plurality of arcuate vanes extendingforwardly from each blade of the impeller. The vanes have respectivecenters of curvature which are spacedapart in a direction which isradial of the rotation axis of the impeller assembly, and which isdisposed at a substantial angle relative to the pitch axis of the blade.The inner vanes on each blade are therefore eccentric with respect tothe rotation axis, and their trailing edges are spaced apart fartherthan their leading edges, with the trailing edges of respective innervanes being nearer the rotation axis than their respective leadingedges. Therefore, fluid being impelled in the forward direction by therotating impeller assembly is urged radially inwardly by centripetalaction of the vanes to converge the fluid stream being impelled in theforward direction.

An important feature of the invention is that the fluid is directed in aconverging beam to make it possible to direct a converging stream offluid to a small area for greatly improved efiiciency of utilization ofthe fluid. Thus, in an air impeller, relatively noiseless spot blowingof air is possible. This obviously has many applications, as forexample, in the cooling of motion picture projectors, where a coolingfan producing maximum directed air flow and a minimum of sound isdesirable.

It is also an important feature of the present invention that itprovides means for varying the focal point or area of the convergingbeam of fluid so that the distance for most effective fluidconcentration or spot blowing may be varied as desired.

It is, therefore, an object of the present invention to provide fan orimpeller means adapted to provide a converging stream of impelled fluidfor concentrating the effect of such fluid, thereby improving theeffectiveness of such fan or impeller means.

An object of the invention is the provision of impeller means accordingto the foregoing object, wherein radially spaced arcuate vanes extendforwardly from blades of the impeller and are eccentric relative to therotation axis of the impeller assembly, thereby imparting radial inwardmotion to fluid impelled forwardly by the impeller assembly to convergethe fluid stream being impelled in the forward direction.

An object of the invention is to provide novel fan or impeller meanswhich are adapted to produce a converging beam of fluid and wherein thedistance of the point of convergence from the fan or impeller means maybe varied.

Still another object of the present invention is to provide fan orimpeller means wherein the impeller blades are capable of eliminatingtip losses whereby to increase efliciency and decrease sound production.

A further object of the present invention is to provide novel fan orimpeller blade constructions wherein the loss 'ice of fluid movingcentrifugally outwardly from the tips of such conventional blades isprevented, thus obviating losses in efficiency and undesirable noiseproduction factors.

Other objects, features and advantages of the present invention willbecome apparent to those versed in the art from a consideration of thefollowing description, the appended claims and the accompanyingdrawings, wherein:

FIGURE 1 is a front elevational view of an impeller constructionillustrative of the principles of the present invention;

FIGURE 2 is a schematic view, in reduced scale, indicating the nature ofconverging beams of fluid flow which may be effected by the impeller ofFIGURE 1;

FIGURE 3 is an enlarged cross-sectional view, taken along the lines 33of FIGURE 1, but showing the blade element in elevation for clarity ofillustration;

FIGURE 4 is an enlarged fragmentary cross-sectional view, taken alongthe lines 4-4 of FIGURE 3, illustrating a detail of the pitch changingmechanism of the impeller;

FIGURES 5 and 6 are schematic views taken generally along the lines 5-5of FIGURE 3, showing the positioning of elements of the pitch changingmechanism in two different positions of adjustment;

FIGURE 7 is an exploded view of the hub components of the impellerassembly of FIGURE 1 showing only one impeller blade, for simplicity ofillustration; and

FIGURE 8 is a schematic showing of a top view of an impeller blade,locking toward the hub thereof, showing various positions of pitchadjustment of the blade.

Referring to the drawings, and particularly to FIGURE 1, there isillustrated an exemplary embodiment of the present invention. Animpeller assembly comprises a hub assembly designated by the referencenumeral 20 and three blades generally designated 22, secured in said hubassembly.

As shown in FIGURE 1, each of the blades 22 has a broad configurationwith substantially parallel side edges without taper and having a curvedouter edge portion extending across the width of the blade.

Extending forwardly from the forward or impelling space of each blade 22are arcuate vanes '26, 28 and 30. Vane 26 is adjacent to the outer orperipheral curved edge of the blade. As indicated in FIGURE 1, vane 26is curved about rotation axis C of the impeller assembly, and has aradius of curvature R Inner vanes 28, 30 have their respective centersof curvature C C spaced apart ina direction or along a line extendingradially from the rotation axis C and at right angles to the pitch axisP of the blade, the pitch axis extending from rotation axis C radiallyoutward parallel to the blade edges. As shown in FIGURE 1, the trailingedges of the vanes are therefore spaced farther apart than their leadingedges, and the trailing edges of the iuner vanes are closer to rotationaxis C than their respective lea-ding edges.

As is common in this art, the impeller blades may vary in pitch from thehub end or root to the tip end, such pitch variation being effective tomore effectively direct the air forwardly. In the illustrated example,it is desirable that the pitch of the blade (in its neutral position)vary from about degrees at its root to about degrees at its tip.

A feature of the present invention is that the blades are mounted insuch a manner that their pitch may be varied. It is considered best todescribe the blade configuration and the eflect of pitch variation atthis point, without regard to specific pitch adjustment means, in orderthat the general purposes and principles of the present invention may bemore easily understood. A specific example of one mounting and pitchchanging assembly is described hereinafter.

In operation, the impeller assembly is rotated clockwise, as viewed inFIGURE 1 to impell a fluid stream in the forward direction, whichdirection is outward as viewed in FIGURE 1, and rightward as viewed inFIGURE 2.

From the foregoing description and from the drawing, it will beunderstood that the eccentric arrangement of the vanes and theabove-described relative spacing of the trailing edges of the vanes,fluid is discharged or impelled from the trailing edges of therespective blades 22 with a radially inwardly directed component ofmotion. The fluid stream being impelled in the forward direction becauseof the pitch angle of the blade is urge-d radially inwardly bycentripetal action of the vanes, thereby effecting convergence of theimpelled fluid stream, as indicated in FIGURE 2. As hereinafterdescribed, the degree of convergence or point of convergence iscontrolled by selective variation of the pitch angle of the blades 22.

Each blade has a greater area or length on one side of its pitch axisthan on the other side, as may be best seen in FIGURES 1 and 8, so thatwhen the pitch is changed by rotating the blade about its axis, therelative positional placement of each vane on the blade is altered.FIGURE 8 illustrates a top view of the blade at various different pitchangles, and FIGURE 2 illustrates the nature of the directed convergentfluid stream as impelled by a blade assembly in corresponding bladeadjustment positions.

In the solid line position of FIGURE 8, the blade is in a neutralcentral position, having normal pitch as previously discussed, thisposition being that shown in FIGURES 1 and 3, and schematically inFIGURE 5. This neutral blade pitch angle produces a fluid stream patternas shown in full lines in FIGURE 2. If the pitch of the blades isincreased to the dotted line position of FIGURE 8, the fluid streampattern is caused to converge to a point or area closer to the impellerassembly, as shown in dotted lines in FIGURE 2.

Conversely, if the blades are each rotated to a lesser pitch as shown indot-dash lines in FIGURE 8, the fluid stream pattern is caused todiverge from the neutral pattern so that concentration of the stream isat a point more remote from the impeller assembly, as shown in dotdashlines in FIGURE 2.

Comparison of the vane positions illustrates that variation of the pitchof the blade causes a change in the relative angle of the tangent to thetrailing edges of the vanes 26, 27, 28 so that the directional forcesimparted to the fluid stream leaving the vanes is varied thereby, aspreviously described.

Thus it may be seen that impeller blade assemblies of the abovedescribed construction are adapted to focus converging streams of fluidto a relatively small area and, by variation of the pitch, to vary thedistance of such area from the blade assembly. It is considered thatmany types of blade mounting and pitch varying means might be utilizedand the drawings herein illustrate one example of such means.

Reference is now made specifically to FIGURES 1, 3, 4 and 7 of thedrawings, which illustrate an exemplary blade mounting and pitch varyingmeans which can be used to form an impeller assembly according to thisinvention.

As shown in FIGURE 3, each of the impeller blades 22 has an integralcylindrical portion at its root end and an enlarged base flange 34integral with the collar at its inner end forming a shoulder to engageretaining bushings 38 and 40.

Base flange 34 in each case, has a radially outwardly extending portionhaving a downwardly extending crank pin 36.

The hub assembly for holding the plurality of blades (three in theillustrated example) comprises a front retaining bushing 38, a backretaining bushing 40, an inter- 4 nal cam element 42 and an adjustingnut element 44, as best shown, disassemble-d, in FIGURE 7.

Retaining bushings 38 and 40 are generally circular members havingmating inner faces 46. Each of the faces 46 has a number ofsemi-cylindrical cut-outs 48 therein. Cut-outs 48 are equi-angularlyspaced on the faces 46 and equal in number to the number of blades inthe assembly. In the assembled relationship of bushings 38 and 40,mating cut-outs 48 provide bearings for the cylindrical portions ofblades 22, as best seen in FIGURE 3. Bushings 38 and 40 are flat ontheir internal surfaces along the lengths of the bushings, as at 50, inthe areas of cutouts 48 to provide flat shoulders for engagement of theshoulders of the base flanges 34 of the blades 22. Bushings 38 and 40have appropriate bores 52 for reception of means (not shown) forsecuring the bushings together. Front bushing 38 has a forward extension54 having a circular bore 56 therethrough for reception of drive shaftmeans (not shown).

The internal cam element 42 is of generally hollow construction, havinga through bore 58 of similar diameter to that of bore 56 of the frontbushing element. The external surface of cam element 42 comprises aforwardly disposed enlarged portion of angular surfaces, as at 59, and areduced cylindrical portion 62. The enlarged portion 59 has a pluralityof flat surfaces 60 adapted to engage the inner flat surfaces of thebase flanges 30 of the blades 22 whereby the blades are clamped securelyagainst radial movement, between surfaces 60 and 50 of the cam elementand of the retaining bushings, respectively. The smaller cylindricalportion 62 of camelement 42 is externally screw-threaded, as best shownin FIGURES 3 and 7, and the periphery of said portion 62 is providedwith cam grooves 64 extending at similar angles to the longitudinal axisof the cam element, such grooves being equal in number to the number offlats 60 and generally aligned therewith so that the crank pin 36 ofeach of the blades 22 extend into a groove 64 when the parts areassembled.

Assembly is effected by insertion of the cam element and the bladeflanges internally of the front and rear retainer bushings, with thecylindrical portions of the blades retained in the bearings formed bythe mating cut-outs 48, with the base flange 34 of each blade retainedbetween the surfaces 50 and 60, and with the crank pin 36 of each of theblades retained in a cam groove 64. The front and rear retainer bushingsare secured together, in face to face relationship, by fastening means(not shown) extending through the bores 52. It should be noted, in theassembly thus far described, that the cam element 42 is not free torotate relative to the retaining bushing elements 38 and 40 by virtue ofthe angular configurations of these parts, but has freedom forlongitudinal movement.

The adjusting nut 44 is then applied to complete the assembly and toprovide means for varying and controlling the pitch of the blades 22.Adjusting nut 44 is a generally annular piece having internal screwthreads, as at 66, of a size to engage the external threads of theportion 62 of the cam element 42 and the assembly is completed bythreading these two pieces together. Obviously, with the adjusting nutagainst the flat rear face of the back retaining bushing 40, movement ofthe nut in either rotational direction is effective to cause cam element42 to move longitudinally, since the cam element is restrained againstrelative rotational movement for reasons previously mentioned. Suchlongitudinal motion of the cam element is effective to cause the crankpins 36 of the impeller blades to be simultaneously and equally shiftedangularly relative to the axes ofthe blades due to longitudinal movementof the grooves 64, which imparts lateral movement to the crank pins.Fastening means, not shown, are provided to hold the nut 44 against therear face of the back retaining bushing 40 and to lock the nut in anyposition of adjustment.

FIGURE 5 illustrates schematically the neutral position of a blade, andFIGURE 6 illustrates the increased pitch position of a blade, thesefigures illustrating the movement of cam grooves 64 and the relativemovement of the crank pins therein.

From the above, it may be seen that the present invention providesimpeller constructions which are capable of increased efliciency offluid propulsion with decreased noise effects and wherein the fluid maybe selectively directed in a convergent stream to a focal point or areawhich is a varying distance from the impeller.

Although a specific embodiment of the present invention has beendescribed and illustrated in detail, it is to be clearly understood thatthe same is by way of illustration and example only; it is to beunderstood that the invention is not limited thereto, as many variationswill be readily apparent to those versed in the art and the invention isto be given its broadest possible interpretation within the terms of theappended claims.

The inventor claims:

1. An impeller assembly rotatable about a rotation axis to provide aconverging fluid stream in a forward direction, said impeller assemblycomprising means for rotating the assembly, a plurality of bladesextending radially outward from said rotation axis, each of said bladesbeing inclined at a pitch angle about its pitch axis to impart forwardthrust to surrounding fluid, a plurality of radially spaced arcuatevanes extending forwardly from the forward face of each of said blades,each of said blades having a larger area on the trailing side of itspitch axis than on the leading side thereof, said respective inner vaneshaving progressively shorter respective radii of curvature in theradially inward direction, the outer vane being adjacent to theperiphery of the blade and being curved, said vanes on each blade havingrespective centers of curvature spaced apart in a direction radially ofthe rotation axis and at a substantial angle relative to the pitch axisof the blade, whereby the trailing edges of the vanes are spaced apartfarther than their leading edges and the trailing edges of respectiveinner vanes are nearer the rotation axis than their leading edges,whereby fluid is discharged from the trailing edges of the blades with aradially inwardly directed component of motion, whereby fluid is urgedradially inwardly by centripetal action of the vanes to converge thefluid stream being impelled in the forward direction, and mechanicalmeans for coordinate variation of the pitch angle of the blades toprovide compound curvatures of respective vanes according to theselected degree of convergence and the selected distance from the bladesof the focus of said stream of impelled fluid.

2. An impeller assembly rotatable about a rotation axis to provide aconverging fluid stream in a forward direction, said impeller assemblycomprising means for rotating the assembly, a plurality of bladesextending radially outward from said rotation axis, each of said bladesbeing inclined at a pitch angle about its pitch axis to impart forwardthrust to surrounding fluid, a plurality of radially spaced arcuatevanes extending forwardly from the forward face of each of said blades,each of said blades having a larger area on the trailing side of itspitch axis than on the leading side thereof, said respective inner vaneshaving progressively shorter respective radii of curvature in theradially inward direction, the outer vane being adjacent to theperiphery of the blade, said vanes having respective curvatures suchthat their trailing edges are spaced apart farther than their leadingedges and such that the inner vanes are eccentric relative to therotation axis and have their trailing edges positioned nearer therotation axis than their respective leading edges, whereby fluid isreleased from the trailing edge of each blade with a radially inwardlydirected motion component to converge the fluid stream being impelled inthe forward direction, and mechanical means for coordinate variation ofthe pitch angle of said blades to provide compound curvatures ofrespective vanes according to the selected degree of convergence and theselected distance from the blades of the focus of said stream ofimpelled fluid.

References Cited by the Examiner UNITED STATES PATENTS 813,074 2/1906Barber. 2,359,466 10/1944 Currie 170170 2,498,170 2/1950 Meier 1701702,574,951 11/ 1951 Benson. 2,763,329 9/1956 Feroy l-160.47

FOREIGN PATENTS 426,729 5/ 1911 France.

9,930 1891 Great Britain. 14,684 1899 Great Britain. 17,935 1910 GreatBritain. 19,354 1911 Great Britain. 3,222 1915 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

SAMUEL LEVINE, Examiner.

E. A. POWELL, JR., Assistant Examiner.

1. AN IMPELLER ASSEMBLY ROTATABLE ABOUT A ROTATION AXIS TO PROVIDE ACONVERGING FLUID STREAM IN A FORWARD DIRECTION, SAID IMPELLER ASSEMBLYCOMPRISING MEANS FOR ROTATING THE ASSEMBLY, A PLURALITY OF BLADESEXTENDING RADIALLY OUTWARD FROM SAID ROTATION AXIS, EACH OF SAID BLADESBEING INCLINED AT A PITCH ANGLE ABOUT ITS PITCH AXIS TO IMPART FORWARDTHRUST TO SURROUNDING FLUID, A PLURALITY OF RADIALLY SPACED ARCUATEVANES EXTENDING FORWARDLY FROM THE FORWARD FACE OF EACH OF SAID BLADES,EACH OF SAID BLADES HAVING A LARGER AREA ON THE TRAILING SIDE OF ITSPITCH AXIS THAN ON THE LEADING SIDE THEREOF, SAID RESPECTIVE INNER VANESHAVING PROGRESSIVELY SHORTER RESPECTIVE RADII OF CURVATURE IN THERADIALLY INWARD DIRECTION,THE OUTER VANE BEING ADJACNET TO THE PERIPHERYOF THE BLADE AND BEING CURVED SAID VANES ON EACH BLADE HAVING RESPECTIVECENTERS OF CURVATURE SPACED IN A DIRECTION RADIALLY OF THE ROTATION AXISAND AT A SUBSTANTIAL ANGLE TO THE PITCH AXIS OF THE BLADE, WHEREBY THETRAILING EDGES OF THE VANES ARE SPACED APART FARTHER THAN THEIR LEADINGEDGES AND THE TRAILING EDGES OF RESPECTIVE INNER VANES ARE NEARER THEROTATION AXIS THAN THEIR LEADING EDGES, WHEREBY FLUID IS DISCHARGED FROMTHE TRAILING EDGES OF THE BLADES WITH A RADIALLY INWARDLY DIRECTEDCOMPONENT OF MOTION, WHEREBY